Overhead door assemblies, such as those generally utilized in loading docks, garages, warehouses, or other enclosed structures, typically include a sectional door assembly that is guided by a vertical track installed on either side of the doorway. Follower elements, such as rollers, are typically affixed to the door assembly and ride within the track as the door is raised and lowered. The door may be raised and stored in a generally vertical orientation, such as found in vertical lift and high lift installations, or the door may travel to a horizontal overhead position, such as found in a standard lift installation. Regardless of configuration, the doors can be manually operated up and down, or motor-driven. To ease the operation of the door, a torsion spring is often used to offset the weight of the door assembly.
Security is an important concern for many homes and businesses, and various locking mechanisms have been devised for overhead doors for this purpose. One such slide lock, disclosed in U.S. Pat. No. 5,489,130, has a base adapted to be mounted on the door, and has a mounting plate and a pair of spaced apart legs. Each leg carries a slide aperture, and one leg includes a lockout hole. A striker plate is attached to the door channel in a position collinear with the base. A spring biased striker is carried by the base and when the door is manually operated, the striker is placed in an operative position where it slides freely through generally aligned slide apertures. When the door is motor operated, the striker may be placed in an inoperative lockout position by placing one end of the striker in the lockout hole. When the striker is in the inoperative lockout position, it cannot contact the striker plate when the door is in the closed position. However, the striker may be easily moved to the operative locking position by overcoming the spring bias, and moving the striker into the slide aperture and thus engageable with the striker plate to lock the door in the closed position.
Another type of lock comprises a spring-loaded locking latch mounted to the door track. As the door is lowered, a plate mounted to the door engages the spring-loaded locking latch and pushes it out of the way. When the door reaches its fully closed position, the plate passes by the locking latch and the latch springs back into place. The latch is designed such that the door-mounted plate cannot move the latch when the door is raised. Thus, the latch provides an obstruction to the plate, and the door is prevented from being raised. A handle on the locking latch moves the obstruction out of the way so the door can be raised.
One of the simplest overhead door locks includes a spring-loaded slider element fastened to the door panel. When the door is closed, the slider element passes through a corresponding slot in the guide track. The slider element includes a hole near the tip portion, so a padlock shackle or the like may pass through the hole once the slider element passes through the slot. When the lock engages the slider element passed through the guide track, the overhead door cannot open.